Move tangent space generation to the vertex shaders
Support diffuse parallax when no normal map is present
Don't use diffuse parallax if there's no diffuse map
Generalize normal-to-view conversion
Rewrite parallax
Don't hijack BSShader::NoLighting for BSEffectShader functionality
(Fallout meshes break if you use the actual emissive color as a base color)
Don't use falloff for textureless NoLighting objects
Use falloff flag for BSEffectShader
